This invention relates to a method of manufacturing the writing tip of a ball point writing instrument and, more particularly, to a method of manufacturing the tip of a ball point writing instrument which can improve the durability by the formation of a fine metallic tube and which can freely design an ink supply passage without restriction in the diameter of the ball.
A conventional method of manufacturing the writing tip of a ball point pen from a fine metallic tube has the steps of inwardly pressing a plurality of positions on the same peripheral edge of the outer peripheral surface in the vicinity of the end of the metallic tube to project and form a seat for a ball on the inner wall, inserting the ball into the end of the tube, and then caulking the edge of the tube.
However, according to the conventional method, the inner diameter of the tube is required to be slightly larger than the diameter of the ball. Accordingly, the size of an ink supply core is limited to smaller than the size of the inner diameter of the tube. Thus, sufficient ink cannot be supplied to the tip, and the ink cannot be supplied particularly in an aqueous ink ball point pen.